An electromagnetic lock is most often used with a keys controller so that not only guests could enter, but also dwellers could get inside the building when there is nobody home to hit the DOOR OPEN button on the apartment device.The best solution is to install the VIZIT-KTM602R, this controller will power both the doorstation and electromagnetic lock (so you do not need a separate power supply unit for your system), and will enable lock release from apartment devices (monitor or handset), with RF keys and by hitting the button for exit. All doorphone devices are wired to the the KTM602R.